The present invention relates to an electronic component which needs to be sealed in an airtight manner and a method of manufacturing the electronic component part. More particularly, the present invention relates to a technique effective in an application to a surface acoustic wave device.
A surface acoustic wave device used as a high-frequency filter for portable telephones, etc., is formed in such a manner that a pair of interdigital electrodes are formed on a surface of a piezoelectric monocrystal chip such as a lithium tantalate (LiTaO3) chip or a lithium niobate (LiNbO3) chip (hereinafter referred to as “SAW chip”), the chip is mounted on a package substrate, and input and output electrodes on the package substrate are electrically connected to the pair of interdigital electrodes.
Ordinarily, a SAW chip is die-bonded to a ceramic package substrate while being positioned so that the chip surface on which a surface acoustic wave propagates, i.e., the surface on which the pair of interdigital electrodes are formed, faces upward, and chip electrodes connected to the pair of interdigital electrodes are electrically connected to internal electrodes on the package substrate by bonding using metallic wires mainly formed of Al or Au. The chip is thereafter sealed with a metallic cap in an airtight manner to form a surface acoustic wave device.
In recent years, there has been a strong demand for reducing the size of components of portable telephones, etc.
To meet the demand, the size of surface acoustic wave devices is reduced by eliminating the wire bonding area in such a manner that the SAW chip is flip-chip-connected to the package substrate.
JP-A-8-316778 discloses a typical device structure relating to such a size reduction method. FIG. 17 shows a diagram schematically showing the device structure.
According to this related art document, a SAW chip 100 having a flow prevention frame 320 formed so as to surround interdigital electrodes 110 is flip-chip-connected to the a package substrate 200 with bumps 400 interposed therebetween, and a sealing resin 310 is injected from a side surface of the SAW chip 100 and is set, thereby forming a surface acoustic wave device.
The sealing resin 310 is stopped by the flow prevention frame 320 at the time of injection. A space 500 is therefore formed on the interdigital electrode 110 surface side to ensure propagation of a surface acoustic wave. The bumps 400 are formed by an Au wire bump method and are connected to the package substrate 200 by a solder or an electroconductive resin.
Known documents relating to the present invention include JP-A-2001-94390, JP-A-4-293311 and JP-A-9-289429 as well as the above-mentioned JP-A-8-316778.